A white-emitting light associated with bluish long afterglow phosphor, Ba13Al22Si10O66 (BASO):Eu, was synthesized by conventional solid-state reaction in air condition. The luminescent properties of the phosphor, including the emission and afterglow spectra, afterglow decay, and thermoluminescence curves, are depicted. Under 365 nm excitation, the intense characteristic 5d-4f emission of Eu2+ was observed, denoting that spontaneous reduction of Eu3+ to Eu2+ occurred in the host lattice. After removing the irradiation source, the phosphor showed a bluish afterglow with the optimum durative time of 43.5 min, owing to the trapping level at 332 K. The possible mechanism of this long-lasting phosphorescence is proposed and discussed. All the results indicate that BASO: Eu prepared in air could be a promising long-lasting phosphor. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3436647] All rights reserved.